It was Shoigu who nominated 57-year old Gerasimov to replace Gen. Nikolai Makarov in the top post, saying:

"He is a military man from head to toe, a man who has served for a long time in the Armed Forces and is respected there. He has enormous experience of work both in the General Staff and on the battlefield."

Makarov, had served as chief of the general staff since 2008, according to The New York Times., which added that the move was not unexpected given Shoigu had a right to install his own team in top military posts.

It was also widely known that Serdyukov's marriage to the only daughter of a key Putin ally, Viktor Zubkov, had hit the rocks.

Zubkov, according to Reuters, was the friend Putin turned to "when he wanted help blowing out his birthday candles 12 years ago."

The 71-year-old one-time prime minister is now chairman of the board of directors at state energy firm Gazprom.

The Times cited Putin as saying via the Interfax news service that:

"The situation in the scientific-technical sphere is changing quickly, and new means of armed warfare are appearing. We should orient ourselves toward optimal means, but still need to maintain a certain stability. I am counting on you and the ministry to establish stable, good collegial work with our leading manufacturers in the defense sector."